Conventionally, an image forming apparatus such as a copy machine or printer can form an image on plural types of recording media with different sizes and thicknesses. As the recording media, paper sheets and OHP sheets and the like are used. In the following description, a sheet is used as an example of the recording media.
A sheet can be supplied to an image forming unit by manual insertion as well as from a paper supply cassette. In the image forming apparatus, an image forming unit including a photoconductive drum is provided. An image is formed on a sheet supplied from a paper supply cassette or a sheet supplied by manual insertion.
By the way, since a sheet is carried to the image forming unit via plural carrying path, a media sensor is installed on each carrying path within the image forming apparatus. Thus, the media sensor discriminates the thickness and type of the sheet passing through each carrying path.
However, there is an inconvenience that the arrangement of the media sensor on each carrying path increases the cost.